A variety of treatment liquids for ink jet recording, containing polyvalent metal ions such as calcium ions are proposed. An image quality can be improved by causing the treatment liquid to contain a certain amount of polyvalent metal ion, and for example, bringing the treatment liquid into contact with a water-based ink on a recording medium by ejecting the treatment liquid prior to an ejection of the water-based ink.
However, the inventors of the present invention found out that there is a case that heating the treatment liquid in an ink-jet head adopting a thermal ink-jet technique (hereinafter referred to as a “thermal ink-jet head”) causes nozzle clogging.